Copper leaching from chalcopyrite concentrate in Cu(II)/Fe(III) chloride system

This study was conducted to develop a novel process for copper recovery from chalcopyrite by chloride leaching, simultaneous cuprous oxidation and cupric solvent extraction to transfer copper to a conventional sulfate electrowinning circuit, and hematite precipitation to reject iron. Copper leaching from chalcopyrite concentrate in ferric and cupric chloride system was investigated using a two-stage countercurrent leach circuit under a nitrogen atmosphere at 97 °C to minimize the concentrations of cupric and ferric ions in pregnant leach solution for subsequent copper solvent extraction while maintaining a maximum copper extraction. A high calcium chloride concentration (110–165 g/L) was used to maintain a high cuprous solubility and enhance copper leaching. With 3–4 h of leaching time for each stage, the copper extraction reached 99% or higher while that of iron was around 90%. With decreasing concentrate particle size from p80 of 26 to 15 μm, the copper extraction increased by about 0.2% while the iron extraction increased by about 2.0%. The concentration of Cu(II) + Fe(III) in the pregnant leach solution was able to be reduced to 0.04 M. When the cupric concentration fell below the above limiting value, the elemental sulfur present was reduced by cuprous ions to form copper sulfide, eventually stopping the leaching of copper. Under this condition, only iron was leached. A very small amount of sulfur (1.2–1.4%) was oxidized to sulfate, resulting in an increase from 3 to 9 g/L in HCl concentration. The extractions of trace metals (Cr, Pb, Ni, Ag and Zn) were 96–100%.     

Leaching behaviour of natural and heat-treated brannerite-containing uranium ores in sulphate solutions with iron(III)

Uranium leaching tests were conducted on two naturally occurring, highly metamict brannerite ores from the Crockers Well and Roxby Downs deposits, South Australia. The ores were leached over a range of temperatures and Fe^(III) and H₂SO₄ concentrations. As well, samples of the ores were calcined at 1200 °C in air to investigate the effect of thermally induced recrystallisation on uranium dissolution. For the unheated samples, a maximum of ∼80% U dissolution was obtained using an Fe^(III) concentration of 12 g/L, an acid concentration of 150 g/L H₂SO₄ and a temperature of 95 °C. The heat treated samples performed poorly under identical conditions, with maximum uranium dissolution of <10% recorded. High uranium dissolution from natural brannerite can be achieved providing; (i) acid strength, oxidant strength and temperatures are maintained at elevated levels (compared to those traditionally used for uraninite leaching), and, (ii) the brannerite has not undergone any significant recrystallisation (e.g. through metamorphism).     

超声波强化低品位氧化锌矿在NH3-(NH4)2SO4-H2O体系中的浸出

研究了低品位氧化锌矿在NH_3-(NH_4)_2SO_4-H_2O体系中的浸出,并利用超声波进行了浸出过程的强化。结果表明,超声波能够强化低品位氧化锌矿在氨性浸出剂中的浸出。在总氨浓度为7.5mol/L,n[NH_4~+]∶n[NH_3]为2∶1,反应温度为40℃,反应时间为60 min,超声波浸出,液固比为5∶1的条件下,锌的浸出率可以达到92.1%。当NH3与(NH4)2SO4的摩尔比为1∶1时,此低品位氧化锌矿在浸出Zn2+所形成的配位化合物为[Zn(NH_3)_4]~(2+)。适当增加氨浓度及反应温度可有效提高锌的浸出率。     

H2SO4-HNO3体系中锌精矿浸出与四氯乙烯萃硫的耦合

研究锌精矿在H2 SO4 HNO3体系中浸出与四氯乙烯萃取硫磺的耦合过程。考察了浸出时间、四氯乙烯的加入对锌浸出的影响。结果表明 ,在 85℃ ,氧气压力 0 1MPa ,H2 SO4 浓度 1 8mol/L ,HNO3浓度 0 2mol/L条件下 ,加入 2 0mL四氯乙烯萃取硫磺时 ,锌浸出率在 3h内达到 99 7% ,与常规浸出相比 ,浸出时间缩短了 5 0 % ,耦合效果明显。     

原子吸收分光光度法测定磷酸锆银钠中的银

先用硝酸 氢氟酸溶解磷酸锆银钠样品，再加氨水(1 1)使其转换成氨性溶液，然后用原子吸收分光光度法测定磷酸锆银钠中的银．本法测定结果与火试金法测定结果一致，相对标准偏差小于0．37％，回收率大于95％．     

在AlCl3和Al（NO3）3-尿素体系中制备Al（OH）3微球颗粒

以AlCl3和Al（NO3）3-为原料，尿素为沉淀剂，草酸铵为添加剂，采用均匀沉淀法制备出超细球形Al（OH）3颗粒．通过SEM和粒度分布手段表征了产品的形貌和大小特征．结果表明．所制备的Al（OH）。颗粒呈球状且分布较均匀，平均粒径为0．85μm．同时对球形颗粒形成的机理进行了初步分析．该制备工艺简单，易实现工业化生产．     

残差修正GM(1,1)模型在煤矿事故预测中的应用

百万吨死亡率是煤炭安全生产的一个重要考核指标,为准确预测煤炭行业安全生产的总趋势,利用灰色系统相关理论,建立了煤炭行业百万吨死亡率的GM(1,1)预测模型。同时鉴于GM(1,1)模型预测精度很低,建立残差修正GM(1,1)预测模型对模型进行了二次修正,并利用该修正模型成功预测出我国煤矿2009年的百万吨死亡率将首次降到1以下,权威机构数据表明,预测结果是可参考的。